High-accuracy traveling table apparatus

Abstract

A high-accuracy traveling table apparatus comprises a workpiece fixing device and a laser mirror for position measurement provided on a table capable of traveling at least in the direction of one axis. The table comprises a mount to which the workpiece fixing device and the laser mirror are fixed and at least one partially coupling member for partially coupling the mount to the table so as to prevent transmission of a distortion of the table to the mount.

What is claimed is: 
     
       1. A high-accuracy travelling table apparatus comprising: (a) a base;   (b) a first table mounted on said base for movement relative thereto in a first direction;   (c) at least two guide ways mounted on said first table and extending in a second direction, said second direction being perpendicular to said first direction;   (d) a second table mounted on said at least two guide ways for movement in said second direction, said second table being preloaded in said first direction relative to said at least two guide ways and said second table having a planar upper surface;   (e) a mount having an upper surface and a planar lower surface that is parallel to said planar upper surface of said second table, said mount being a little thinner than said second table;   (f) a partial coupling portion extending from a central portion of said planar upper surface of said second table to a central portion of said planar lower surface of said mount, said partial coupling portion providing the sole support for said mount and the length of said partial coupling portion being small relative to the thickness of said mount, whereby said planar lower surface of said mount and said planar upper surface of said second table are separated by a gap the thickness of which is nominally equal to the length of said partial coupling portion, and the thickness of said gap is small relative to the dimensions of said partial coupling portion perpendicular to said gap;   (g) a workpiece fixing means mounted on said upper surface of said mount; and   (h) a laser mirror mounted on said upper surface of said mount.   
     
     
       2. The high-accuracy traveling table apparatus according to claim 2, wherein said partially coupling means is a means for fixing said mount to said table, and the fixing means is formed independently of said mount and said table. 
     
     
       3. The high-accuracy travelling table apparatus according to claim 2, wherein the thickness of said mount is thinner than that of said table, and said mount is formed of a material having a lower coefficient of heat expansion than that of aluminum. 
     
     
       4. The high-accuracy travelling table apparatus according to claim 3, wherein said mount is formed of a material having a greater rigidity than that of aluminum. 
     
     
       5. The high-accuracy travelling table apparatus according to claim 1, wherein said second mount and said second table are integrally formed with each other so as to fix said mount to said table only at the central portions thereof, and said integrally formed center portions comprise said partially coupling means. 
     
     
       6. The high-accuracy travelling table apparatus according to claim 1, wherein a gap is formed between said mount of said second table, except said partially coupling means, so as not to allow said second table which has been distorted to contact said mount.